1. Field of the Invention
The present invention relates to a data management method and a data management system for managing data through a communication line.
2. Description of the Related Art
At the present time, as the means for preventing the transfer to other parties of data, music, video, and other software obtained by a user from a data storage apparatus of a data center (hereinafter referred to as "data etc."), use has been made of the method of burying the control data relating to the data management such as the prohibition of copying or reediting (hereinafter referred to as the "control data") in the data etc. at the time of transfer of the data etc. from the data center to the user terminal and the method of deliberately scrambling the data etc. and giving at the same time decoding data.
The methods of transfer of control data and deliberate scrambling and giving decoding data are performed using a communication channel (hereinafter referred to as a data channel) after that communication channel is formed between the user terminal and the center in the same way as the transfer of the data etc.
In the above-mentioned conventional methods shown above, it is not possible for the data center to manage the data etc. after transfer to the user terminal. Therefore, up to now, there has been the problem that the data center could not determine if the data etc. was being copied or reedited or the deliberately scrambled data was being maliciously restored.